No hot air until accelerating is typical of low coolant level but it can also be caused by a leaking cylinder head gasket. A leaking head gasket can also cause overheating because if combustion gases sneak into the cooling system it can pool under the thermostat and make it not open. Thermostats have to be hit with hot liquid to open. Hot air wont do it. When the thermostat stays closed, it blocks coolant flow to the radiator.
Your mechanic can do a chemical test at the radiator to check for a leaking head gasket. That involves drawing air from it while the engine is running, through a glass cylinder partially-filled with a special dark blue liquid. If combustion gases are present, the liquid will turn bright yellow.
Friday, February 14th, 2014 AT 2:14 AM